1. Field of the Invention
The invention relates to a system for deployment of an anastomosis device and a method of performing anastomosis. In a preferred embodiment, the system can be used for piercing a vessel wall as an initial step in forming a sutureless connection between a bypass graft and a blood vessel, and the subsequent deployment of an anastomosis device.
2. Brief Description of the Related Art
Vascular anastomosis is a procedure by which two blood vessels within a patient are surgically joined together. Vascular anastomosis is performed during treatment of a variety of conditions including coronary artery disease, diseases of the great and peripheral vessels, organ transplantation, and trauma. In coronary artery disease (CAD) an occlusion or stenosis in a coronary artery interferes with blood flow to the heart muscle. Treatment of CAD involves the grafting of a vessel in the form of a prosthesis or harvested artery or vein to reroute blood flow around the occlusion and restore adequate blood flow to the heart muscle. This treatment is known as coronary artery bypass grafting (CABG).
In the conventional CABG, a large incision is made in the chest and the sternum is sawed in half to allow access to the heart. In addition, a heart lung machine is used to circulate the patients blood so that the heart can be stopped and the anastomosis can be performed. During this procedure, the aorta is clamped which can lead to trauma of the aortic tissue and/or dislodge plaque emboli, both of which increase the likelihood of neurological complications. In order to minimize the trauma to the patient induced by conventional CABG, less invasive techniques have been developed in which the surgery is performed through small incisions in the patients chest with the aid of visualizing scopes. Less invasive CABG can be performed on a beating or stopped heart and thus may avoid the need for cardiopulmonary bypass.
In both conventional and less invasive CABG procedures, the surgeon has to suture one end of the graft vessel to the coronary artery and the other end of the graft vessel to a blood supplying vein or artery. The suturing process is a time consuming and difficult procedure requiring a high level of surgical skill. In order to perform the suturing of the graft to the coronary artery and the blood supplying artery the surgeon must have relatively unobstructed access to the anastomosis site within the patient. In the less invasive surgical approaches, some of the major coronary arteries including the ascending aorta cannot be easily reached by the surgeon because of their location. This makes suturing either difficult or impossible for some coronary artery sites. In addition, some target vessels, such as heavily calcified coronary vessels, vessels having very small diameter, and previously bypassed vessels may make the suturing process difficult or impossible.
An additional problem with CABG is the formation of thrombi and atherosclerotic lesions at and around the grafted artery, which can result in the reoccurrence of ischemia. The thrombi and atherosclerotic lesions may be caused by the configuration of the sutured anastomosis site. For example, an abrupt edge at the anastomosis site may cause more stenosis than a more gradual transition.
Accordingly, it would be desirable to provide a sutureless vascular anastomosis device which easily connects a graft to a target vessel and can be deployed in limited space. It would also be desirable to provide a sutureless anastomosis device which is formed of one piece and is secured to the target vessel by a one piece tool which can perform both the initial piercing of the tissue and deployment of the anastomosis device.
According to a preferred embodiment, the present invention relates to a deployment system for forming an incision in a wall of a target vessel and delivering an anastomosis device for connecting an end of a graft vessel to a target vessel at the site of the incision. The deployment system preferably includes a trocar, a tissue punch having a piercing element at a distal end thereof for being advanced through the trocar to form a puncture and for thereafter being withdrawn from the trocar, a holder tube slidably disposed within the trocar, an expander tube for cooperating with the holder tube, and a rotatable control, whereby rotation of the control causes advancing and withdrawal of the tissue punch and relative slidable movement between the trocar, the holder tube, and the expander tube for deployment of the anastomosis device. In a further aspect of the invention, the trocar is a tubular member having a passage therein through which the anastomosis device is deliverable to the incision site. Still further, the piercing element comprises a cutting blade which is movable with respect to the trocar such that the cutting blade can be moved from a cutting position at which the cutting blade is exposed to a retracted position at which the cutting blade is not exposed.
According to a further aspect of the present invention, the preferred embodiment is directed to an anastomosis device deployment system including a deployment tool having a rotatable control knob, a holder tube attached to the tool, the holder tube having a distal end configured to hold the anastomosis device with an attached graft vessel, and an expander positioned within the holder and slidable with respect to the holder to a position at which the expander is positioned within the anastomosis device and radially expands the anastomosis device. The system further preferably includes a trocar movable with respect to the holder tube to form an opening in a target vessel to receive the anastomosis device and attached graft vessel. Still further, the deployment tool includes three cam grooves, and the trocar, holder tube and expander each have a follower member engaged in one of the cam grooves to move the trocar, holder tube and expander with respect to one another upon rotation of the control knob.
In accordance with a further embodiment of the invention, a method of performing anastomosis includes providing a deployment tool having a trocar, an expander tube, a holder tube holding a one-piece tubular anastomosis device having an end of a graft vessel everted around the anastomosis device, and a rotatable control knob for moving the trocar, the expander tube and the holder tube relative to one another. The method includes rotating the control knob to puncture a target vessel with the trocar, rotating the control knob to insert the tubular anastomosis device with everted graft vessel into the puncture in the target vessel, rotating the control knob to radial expand the tubular anastomosis device with the expander tube to cause a portion of the anastomosis device to fold outward forming a first annular flange, and rotating the control knob to form a second annular flange on the anastomosis device to trap a wall of the target vessel between the first and second annular flanges and seal the graft vessel to the target vessel. According to a preferred embodiment of the method, enlargement of an internal diameter of the anastomosis device with the expander tube causes the formation of the first flange. According to a further aspect of the invention, the device is expanded by an expander in the form of an inflatable balloon. Still further, in a preferred method of the invention, the radial expansion of the anastomosis device causes a portion of the device to bend at a plurality of hinges to form the first and second annular flanges. The deployment tool may further comprise a tissue punch, wherein rotation of the control knob causes advancement of the tissue punch into the target vessel prior to advancement of the trocar.
Preferably, the target vessel is an aorta and the method is performed without occlusion (i.e., clamping) of the aorta. The end of the graft vessel and the edges of the incision in the target vessel can be captured between the first portion and the second portion so that the end of the graft vessel abuts an outside wall of the target vessel. The anastomosis device can be expandable from a first configuration to a larger second configuration where the anastomosis device is expanded with an expander to cause a portion of the anastomosis device to fold outward forming the first flange. In this regard, the first flange holds a portion of the graft vessel in contact with an inner surface of the target vessel.